The invention relates to a manipulator for forging machines, for example multiple-ram forging machines with a plurality of rams acting radially on the forging, in which the workpiece is moved axially according to the forging sequence and the feed drive of the manipulator takes place at a constant speed. An actively controllable, axially effective superposed drive acts intermittently on the gripper axle of the manipulator, at least one hydraulically working piston/cylinder unit being provided for supporting the axially displaceable gripper axle in relation to the manipulator housing.
In a known version, the gripper axle is mounted axially displaceably in the manipulator housing and is supported axially via spring elements, so that the gripper axle can move in both directions. During the pressure-contact phase, the workpiece is kept stationary by the forging tools. Because the drive continues to run at constant speed, the gripper axle shifts counter to the spring tension. After the pressure-contact phase has ended, the axle is returned again via the tensioned spring. In the course of the return movement and in interaction with the accelerated masses, not only is the middle position reached by the return, but also the system oscillates into the opposite spring element and even partially back again, the relative speed of the gripper axle and workpiece in relation to the forging machine diminishing to zero or approximately zero before the new pressure-contact phase of the next work cycle begins.
In the oscillating system, the spring tension, the mass forces and the speeds are in direct physical relationship. This system can ensure a proper functioning only when the constructively determined parameters are maintained. Even in the different types of machining (roughing, precision machining), the ratio of the contact time and idle time constitutes a variable and therefore different parameters are obtained for the oscillating system..
The oscillating system has to be tied to a fixed stroke frequency of the forging machine. Since the mass varies as a function of the workpiece size, an adverse effect on the oscillating system as a result of a change of mass arises.
It is known, furthermore, to provide a manipulator control forging machines, in which the forging press and forging manipulator can be controlled in synchronism. The manipulator is moved continuously at a mean speed regulated to the stroke time and to the feed desired for the forging work, whilst the gripper of the manipulator executes together with the forging a movement intermittent in relation to the carriage and the position necessary for the next press stroke is therefore reached in a shorter time than the manipulator as a whole. A controllable axial superposed drive acts for a predetermined time on the axially displaceable gripper axle of the manipulator At least one hydraulically working piston/cylinder unit is provided for supporting the axially displaceable gripper axle relative to the housing.